The subject matter of this disclosure relates generally to high voltage, high power multi-level drive structures, with many input and output phases, and more particularly to a multi-level drive structure that combines the architectures of classical multi-level neutral-point-clamped (NPC) and multi-level neutral-point-piloted (NPP) converter topologies.
A multiplicity of multi-level drive structures have been proposed. One known multi-level drive structure is the classical three-level neutral-point-clamped converter 10 such as shown in FIG. 1. Another known multi-level drive structure is the three-level neutral-point-piloted converter 20 such as shown in FIG. 2. Although known NPC and NPP converter structures have proven to be advantageous in numerous applications, these known converter structures leave room for improvements in both operational efficiency and waveform quality.
Yet, another known multi-level drive structure 30 is illustrated in FIG. 3. Although the multi-level converter 30 structure shown in FIG. 3 offers improvements over the NPC and NPP converter structures, it still leaves room for improvements in operational efficiency as well as reliability.
Still another known multi-level drive structure is depicted in FIG. 4 that illustrates a five-level neutral-point-piloted converter structure 40. The converter structure 40 shown in FIG. 4 employs flying capacitors 42, 44 to provide a flying capacitor (FC) based multi-level converter. Such converter topologies have proven to be advantageous in certain high voltage, high power drive applications, but continue to leave room for improvements in operational efficiency.
FIGS. 5-8 illustrates further classical converter topologies known in the art including a cascaded bridge converter structure 50, a modular multi-level converter structure 60, and active neutral point converter structure 70 and a hybrid converter structure 80. Similar to known NPC and NPP converter structures, these classical converter structures continue to leave room for improvements in operational efficiency and/or waveform quality and/or reliability.
In view of the foregoing, there is a need to provide a high voltage, high power multi-level drive topology that provides further improvements in operational efficiency and/or waveform quality and/or reliability beyond that afforded by known multi-level converter structures.